UPDATE 1-Exelon completes nozzle work at NJ Oyster Creek reactor

By Scott DiSavino Nov 27 (Reuters) - U.S. power company Exelon Corp completed repairs on a reactor vessel nozzle at the Oyster Creeknuclear power plant in New Jersey, federal nuclear regulatorssaid Tuesday. "The company's weld overlay repairs to a reactor vesselnozzle found recently to have two "indications" (flaws ordefects) are now completed," Neil Sheehan, a spokesman for theU.S. Nuclear Regulatory Commission (NRC) said in an email. "Our inspectors will review the final ultrasonic testingdata to ensure we are satisfied with the repair work," he said. On Monday, Exelon said the 615-megawatt (MW) plant was in asafe shutdown mode and it would fix the nozzle before thereactor could exit a refuelling outage. The company however did not say when the 43-year old unit -the oldest operating reactor in the United States - would exitthe outage, which began on Oct. 22. Separately, Exelon told the NRC in an event report earlyTuesday it found a pinhole leak of about 2 to 3 drops per minuteduring testing of the reactor head spray line. The leak isthrough an earlier weld. The NRC said the line was part of a reactor vessel headcooling system, which is only used when the plant is shuttingdown. Its purpose is to assist in reactor vessel head coolingduring shutdown. The company said it was investigating the cause of the leakand developing a plan to fix the problem. The NRC said its specialists will engage Exelon on the leakand review the company's investigation into the flaw and itsrepair plan. Earlier, the NRC said it had a metallurgist at Oyster Creekto make sure the agency was satisfied with the nozzle overlaywork. Exelon said the indication in the nozzle was found during adye inspection of the reactor. The NRC said the nozzle is used for the control rod drivemechanism. Control rods are made of materials that absorbneutrons and are used to control the power output or shut areactor. To fix the indication, which the NRC said was not a crackbut could grow into a crack if left unaddressed; Exelon grounddown the metal around the indication and welded a metal overlayon top of the site to keep it within engineering standards forthickness.

SANDY ALERT All refuelling outages are busy, but this one was especiallyactive for Oyster Creek. The plant declared an alert on Oct. 29 as water rose in theplant's water intake structure due to the rising tide, and windand storm surge from Hurricane Sandy. The NRC said there were no safety concerns because the plantdid not have to contend with a reactor shutdown since Sandypassed through the area when the unit was already shut forrefuelling. The NRC however on Nov. 13 said it started a specialinspection to gain a better understanding of how the intakewater level information was monitored and communicated duringthe Sandy event.

TIMELINE: 1965 - Construction started 1969 - Plant enters service, making it the oldest operating nuclear plant in the United States 1999 - GPU Inc agreed to sell reactor to AmerGen for $10 million 2003 - Exelon bought AmerGen in 2003 2005 - Exelon applied with the NRC to extend the operating license before the license was to expire in 2009 2009 - NRC renewed the reactor's original 40-year operating license for another 20 years 2010 - Exelon agreed with New Jersey to shut reactor in 2019 to avoid building cooling towers 2019 - Oyster Creek reactor to shut 2029 - Operating license expires